NAME

       VerticesComp,  VerticesView, PSVertices - abstract base classes for vertexed graphical component subjects
       and their views and PostScript external representations

SYNOPSIS

       #include <Unidraw/Components/vertices.h>

DESCRIPTION

       VerticesComp is an abstract base class for graphical components whose geometry can be expressed as a list
       of  coordinate  pairs.   VerticesComp  uses  a  Vertices  graphic  to  store  its  graphical  attributes.
       VerticesView is an abstract GraphicView subclass for displaying a VerticesComp. PSVertices is an abstract
       PostScriptView for subclasses that externalize VerticesComp information in PostScript form.

VERTICESCOMP PUBLIC OPERATIONS

       Vertices* GetVertices()
              Return  the Vertices graphic that defines the vertices's attributes.  GetVertices is simply a more
              specific form of the GetGraphic operation.

VERTICESCOMP PROTECTED OPERATIONS

       VerticesComp(Vertices* = nil)
              The constructor takes  an  optional  vertices  graphic  that  defines  the  component's  graphical
              attributes.

VERTICESVIEW PUBLIC OPERATIONS

       virtual void Interpret(Command*)
              VerticesView interprets AlignToGridCmd to align its first vertex to the grid.

       virtual void GetVertices(Coord*& x, Coord*& y, int& count)
              Return  the  view's vertices in canvas coordinates.  GetVertices allocates new arrays each time it
              is called.

       VerticesComp* GetVerticesComp()
              Return the subject.

VERTICESVIEW PROTECTED OPERATIONS

       VerticesView(VerticesComp* = nil)
              Initialize a VerticesView, optionally supplying the subject.

       virtual void CreateHandles()
              VerticesView redefines CreateHandles  to  create  a  RubberHandles  object  that  draws  a  handle
              coinciding with each vertex.

       virtual boolean VertexChanged()
              Returns  whether  or  not  the  vertices as stored in the view are different in any way from those
              stored in the subject.  The Update function relies on the result to determine whether to  recreate
              the   view's   structured   graphic   based   on   the   subject's.    VerticesView::VertexChanged
              (conservatively) returns false by default; subclasses should redefine this function to make a more
              discerning decision, thereby increasing the efficiency of the update operation.

PSVERTICES PROTECTED OPERATIONS

       PSVertices(VerticesComp* = nil)
              Initialize a PostScript external representation of the given subject, if any.

       virtual const char* Name()
              Subclasses should redefine Name to return the proper tag for the object in the  PostScript  output
              as required for idraw compatibility.

SEE ALSO

       GraphicComp(3U),  GraphicView(3U), Grid(3U), PatternCmd(3U), PostScriptView(3U), Vertices(3U), align(3U),
       idraw(3I)

Unidraw                                          23 January 1991                                VerticesComp(3U)